A rifle grenade is a grenade that uses a rifle-based launcher to permit a longer effective range than would be possible if the grenade was thrown by hand. The practice of projecting grenades with rifle-mounted launchers was first widely used during World War I and continues to the present, with the term “rifle grenade” now encompassing many different types of payloads including high explosive, fragmentation, and anti-tank warheads as well as concussion, smoke, incendiary, and flare missiles.
A wide variety of rifle grenades have been developed over the past 100 years. The rod-type rifle-grenade is a standard hand-grenade with a metallic rod attached to the base so it can be fired from a standard rifle. They were developed prior to World War I. The following steps are followed when using a rod-type rifle grenade:    1. Insert the rod-type rifle-grenade down the barrel of a standard rifle.    2. Insert a special blank cartridge (with a launch charge but no bullet) into the rifle's chamber.    3. Place the rifle's butt-stock on the ground.    4. While holding the grenade's safety-spoon with one hand, remove the safety pin with the other.    5. Place free hand on the rifle's grip and prepare to fire.    6. Release the grenade's safety-spoon, quickly place said hand on the rifle's forestock, and immediately fire the rifle.
This design has a number of disadvantages. If the soldier does not immediately launch the grenade, the grenade will time-out and explode, resulting in serious injury or death. Repeated launching of rod-grenades also places an extreme amount of stress on the rifle barrel and the rifle itself, which quickly makes the rifle useless as an accurate firearm. As a result, the rod-type rifle-grenade fell from favor.
The cup-type launcher replaced the rod-type rifle-grenade during World War I. A soup can-shaped launcher is attached to a rifle's muzzle. The cup-type launcher can launch a standard hand-grenade or a purpose built cup-type grenade. The following steps are followed when using a cup-type grenade:    1. Insert a grenade into the cup launcher. When using a standard hand-grenade remove the safety pin; the cup holds the safety-spoon in place until the grenade launched.    2. Insert a special blank cartridge into the rifle's chamber.    3. Place the butt-stock of the rifle on the ground and fire from this position.
The cup-type launcher has the advantage of using standard hand-grenades. However, the need to load a blank cartridge into the rifle's chamber in order to launch the grenade proved to be clumsy in combat, or blanks may not be available when the need arises. Moreover, when a blank is loaded, the rifle is rendered essentially non-functional for conventional use when the need may arise.
This difficulty lead to the development the French “Vivien and Bessières” shoot-through grenade (or VB grenade). As the name implies these grenades permit the use of live ammunition to launch the grenade. The VB grenade has a hole through the middle that permits the passage of a standard bullet through the grenade. The bullet arms the grenade, the expanding gases launch the grenade, and the grenade explodes 8 seconds later. These characteristics eliminate the need for a special blank round to launch the grenade. The following steps are followed when using a VB grenade:    1. Insert VB grenade into the cup-type launcher.    2. Place the butt-stock of the rifle on the ground and fire from this position.
The 22 mm type rifle grenade launcher was developed prior to World War II. This type of launcher is attached to a rifle's muzzle and allows for the use of a wide range of rifle-grenades, from powerful anti-tank rounds to simple finned tubes with a fragmentation hand-grenade attached to the end. These rifle-grenades come in “standard” type, which are propelled by a blank cartridge inserted into the chamber of the rifle, or “bullet trap” and “shoot through” types, which allow the use of live ammunition. All modern 22 mm rifle-grenades explode on impact. All standard issue NATO rifles are capable of launching STANAG type 22 mm rifle grenades from their integral flash hiders without the use of an adapter. However, a blank cartridge is required. Modern bullet-trap rifle-grenades such as the French APAV40 can be fired as fast as a soldier can place a grenade on an FAMAS rifle's muzzle and pull the trigger. The APAV40 has a bullet trap consisting of a piece of copper placed at the bottom of the tube. Its rear part has a recess for absorbing the conventional ball ammunition and a shock absorber with radial vents and a central vent on its front. The APAV40 has to impact the target in order to ignite. The following steps are followed when using a bullet trap grenade:    1. Place 22 mm rifle-grenade over the spigot attachment or the rifle's flash hider.    2. Aim at target and fire rifle.
By the late 1970s, rifle grenades and the use of rifles as launchers began to be replaced by dedicated grenade launchers. First seen in the United States armed forces, these grenade launchers generally took the form of a separate weapon, such as the M79 grenade launcher. Alternatively, under-barrel attachments to assault rifles were employed, such as the M203 grenade launcher attached to an M-16 rifle.
Modern combined arms doctrine dictates that every infantry unit should have a certain percentage of dedicated grenadiers, or soldiers equipped with a grenade launcher or combination rifle/grenade launcher. The criticism of this doctrine is that if the grenadiers in a group are disabled or separated from the group, then the group has completely lost the grenade launcher as a heavy fire support. With the addition of rifle grenades launched by standard rifles using standard ammunition, each soldier can be equipped with a small number of rifle grenades, so every individual soldier has some form of heavy firepower.
Therefore, a need exists for a new and improved launched smoke grenade that uses a standard unmodified M-16 rifle and live ammunition as a launcher. In this regard, the various embodiments of the present invention substantially fulfill at least some of these needs. In this respect, the launched smoke grenade according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in doing so provides an apparatus primarily developed for the purpose of providing a smoke grenade that is launched from a standard unmodified M-16 rifle using live ammunition.